Answer:
x =3.9
Step-by-step explanation:
Since this is a right triangle we can use the Pythagorean theorem
a^2 + b^2 =c^2
x^2 + (5x)^2 = 20 ^2
x^2 + 25x^2 = 400
Combine like terms
26 x^2 = 400
Divide each side by 26
x^2 = 400/26
Take the square root of each side
sqrt(x^2) = sqrt(400/26)
x = sqrt(400/26)
x =3.922322703
Rounding to the nearest tenth
x =3.9
